Nukes Against Earth-Impacting Asteroids

TopSpin writes "Flight International reports that scientists at the Marshall Space Flight Center have developed designs for an array of asteroid interceptors wielding 1.2-megaton B83 nuclear warheads. The hypothetical mission for these designs is based on an Apophis-sized Earth impactor 2 to 5 years out. According to NASA, 'Nuclear standoff explosions are assessed to be 10-100 times more effective [at deflection] than the non-nuclear alternatives analyzed in this study." On April 13, 2029, Apophis will pass closer to earth than geosynchronous satellites orbit.

I, for one, welcome our...

extinction-level-event nuke-shielded overlords!

-WtC

*please insert sig*

Re:I, for one, welcome our...

I, for one, welcome our... extinction-level-event nuke-shielded overlords!

Kree Hol Mel.... Apophis!

Re:I, for one, welcome our...

Dont worry, TFA clearly states:

According to the WSS, there are no known safety issues associated with the B83.

Apophis should be able to be destroyed...

with an alternate reality gateway, and a crack commando team consisting of a linguist with allergies, a wise cracking Colonel, a brilliant astrophysicist, and someone with a horrible gastronomical infection. Also some grenades.

APOP-Whut?

In case you were wondering, Apophis is the Greek form of the name for the Egyptian Demon Apep [wikipedia.org].

Otherwise known as the personification of all that is evil.

Re:APOP-Whut?

"In case you were wondering, Apophis is the Greek form of the name for the Egyptian Demon Apep."

Thanks. Because if there's one thing that you can be sure about the average Slashdot reader it's that none of us has ever seen an episode of Stargate SG-1, and thus the name Apophis, and associating that name with evil personified, would be totally new to us all.

FUD alert..

Apophis was lowered to 0 on the Torino scale sometime last fall. I'm not sure why it even warranted a mention in this particular context..

Re:FUD alert..

"Apophis-sized" implying that the plans would be equally valid for similarly sized bodies even with Apophis missing us in a few decades.

Re:FUD alert..

Apophis is a perfect example of how flawed the current system for identifying potentially hazardous near-earth asteroids is. A two body analysis showed that it was on a collision course, but a more intensive three body analysis showed it would miss by a lot. Thing is, the opposite could potentially also be true - a two body analysis might show that an object is not a threat when, in fact, it is and a more heavy analysis would show that. We need more resources dedicated to this very real threat to our planet. Only with early detection do we have any chance of deflecting a planet killer.

Why do we need nukes?

Couldn't we simply send a small spacecraft to intercept the asteroid? Say, a small craft, probably with one primary weapon that has plenty of ammo... probably shaped like a triangle, I think. It could use this "weapon" to then shoot at any incoming asteroids.

Of course, the weapon wouldn't be as powerful as a nuke, and would probably split the asteroid in, say, half. The ship would then have to shoot both halves, breaking them again into half, creating four asteroids where just one was originally. The pilot would repeat this process until the asteroid is broken into such small pieces that they'll be deflected by earth's atmosphere.

I'm still working on how the ship and asteroid fragments would warp to the other side of the field when they hit the edges, though... probably why NASA decided against this approach. That, and they wanted to avoid ripping off The Last Starfighter too much.

I'm definitely following this story!

Because I don't want to miss a thing!

What about other options?

They claim 10-100 times more effective than other methods. First of all they dont define more effective. Second of all, they seem to dismiss ideas like a gravity tug out of hand as not developed enough.

The idea of throwing nukes at an object of potentially unknown size bugs me, especially when much more controlled options exist. All that needs to be done is to nudge the NEO out of small zones known as "keyholes" that are small, finite portions of space where the pull of the Earth will push the object into a collision course on its next orbit rather than another random non-intersecting orbit.

A fairly massive object (something a Delta IV Heavy could launch) would be perfectly capable of handling an Apophis sized object with enough lead time (on the order of years, but certainly less than decades), by flying in formation with the object in the right location to shift its orbit slightly. This is a lot easier than Apollo, which we pulled off in less than 10 years, so to dismiss it as too difficult is ridiculous, and it seems a lot more responsible than launching nukes at an object we dont fully understand.

Just my thoughts anyway.

Re:what if they miss hteir shot

I have to wonder if you where just kidding or are don't know anything about nuclear weapons.
From the 40s up through I think the 70s many nuclear weapons where detonated in the atmosphere. While it was a really bad plan life pretty much kept on living. A miss would probably not hit the earth and a launch accident wouldn't cause a nuclear detonation. A common method of safeing a nuclear weapon involves filling the pit with a neutron absorbing wire. Once the weapon leaves the atmosphere a motor will pull the wire out of the core and only then the weapon will be capable of nuclear detonation. Not only that most modern weapons are much cleaner then the bombs of the 50s.
So I wouldn't to see them launching them daily I think risk to benefit ratio is pretty good.

Re:clean nukes are just old propaganda

It is not true at all that "most modern weapons are much cleaner than the bombes of the 50s. In fact the fusion yield of modern weapons accounts for less than 40% of the total yield, most of the yield actually comes from fission of the uranium container that doubles as a reflector. "clean weapons" can be produced by using non-fissionable reflector like lead, this causes at leat 40% increase in total weight of the weapon design while reducing the total yield approximately to one half. The example of a super-clean bomb is Tsar Bomba that exploded at about 52MT, a lead-reflected test of a 100MT design.

For military the intense radiation from fission of the uranium reflector is an "added bonus". The premium in thermonuclear warhead design is on light weight and narrow diameter (long narrow-cone re-entry vehicles have much better precision than fat ones) in compromise with low cost (low consumption of expensive materials like tritium and plutonium) and high reliability.

The clean weapon was a temporary fad in 50s and early 60s, it was used by rival weapon design team to justify existence of Lawrence Livermore Laboratory and was oversold, being seized upon by politicians it got disproportionate coverage in print - but it never resulted in a weaponised design. The reality is that even a "clean" bomb designs are still an order of magnitude dirtier than Hiroshima and don't offer any military advantage so they are not stockpiled. The peaceful uses of clean nukes like digging harbors and re-livening natural gas and oil fields never materialized as it turned out that produced crater (or gas) was unpleasantly radioactive (because of neutron-induced radiation, with long-lived radioisotopes like C-14 and tritium)

Re:what if they miss hteir shot

Even assuming that you are joking, this is a non-issue. The atmosphere and magnetosphere shield us from a metric butt-ton of solar radiation. Space is not pristine, and at risk of being damaged. Space is trying to kill us all, whether by pulling us atom from atom (vacuum), freezing us solid, radiating us 'til we're crispy, or throwing large rocks at us. Just offa the top of my head, my guess is that you could probably fly through the location of a thermonuclear blast in space minutes after the event.

Re:oh noez!

It would go off but would look nothing like an atmospheric burst. It would be a really bright spherical event that mostly produced an incredibly intense flux of gamma rays, with some neutrons as well. The only actual matter to heat up would be the bomb itself, so the size of the visible explosion would be small, but unbelivably bright. The idea is to cause this really intense light and gamma ray burst to heat the surface of the asteroid enough to cause vaporization and ablation. That would cause a small thrust that changes the direction of the asteroid enough to miss the Earth.

Re:oh noez!

It would be completely different.

The first destructive effect is caused by the radiated energy itself, but most of the destructive power of an atmospheric nuclear detonation comes from the quick heating and displacement of huge quantities of air that creates the explosive shock-wave.

In space, only the radiated energy of the detonation remains. While it would be sufficient to deflect an asteroid, a nuke is nowhere near as destructive in deep space than it is on Earth.

Re:Yes

I'd also like to know how the shark moves through the air.

Re:Star Wars Fakeout

This isn't the conspiracy you're looking for.

They can go about their business.

Move along.

Re:Star Wars Fakeout

We're spending it on Star Wars.

Solution: Assassinate George Lucas.

Re:Star Wars Fakeout

The chances of getting hit by an asteroid are extremely small.

That's true. The potential damage from getting hit is very, very large though - and the probability isn't quite small enough to completely discount. Major meteor impacts have occurred with some frequency on a geological time scale - it seems prudent to actually do the risk assessment and take appropriate action if necessary.

As for the foreign energy independence issue, sure that's important. That doesn't mean that astronomers who specialize in asteroids should drop their careers for it any more than you should drop your career (whatever it is) to worry about potential meteor impacts.

Re:Star Wars Fakeout

The large damage from theoretically possible asteroid impacts doesn't make it any more likely that they will happen. That's a statistical fallacy.

Huh? Of course the damage it would do doesn't make the event more likely, but it makes the event more serious.

If one event is likely, but has minimal impact if it occurs, it might be worth ignoring, in order to concentrate on a less likely event that has disastrous consequences.

Since a large asteroid impact could be a mass extinction event, something capable of wiping out our entire ecosystem -- not to mention civilization -- even if it's unlikely, it's worth working to prevent. Compared to that, everything except the possibility of nuclear war (or equally disastrous environmental collapse) pales in comparison.

Re:this is not armageddon NASA :)

you just made a single asteroid into a hail of dangerous shrapnel.

Shrapnel == Greater Cross Section
Greater Cross Section == Atmosphere has greater effect on projectile
Atmosphere has greater effect on projectile == Energy dissapated over wider area
Energy dissapated over wider area == No boom today. Boom tomorrow. Always boom tomorrow.

Re:Uh oh...

Or, you can use the Doomsday Algorithm [wikipedia.org].

Re:Quick !

Get Ben Affleck's spacesuit ready.

OK, I've drilled holes in the helmet and emptied the oxygen tank...